There is a big problem with the perspective that you are bringing to this issue. You're speaking from the assumption that science has a complete understanding of human nutrition, which it clearly does not. The chemical processes that we are talking about are currently irreducibly complex. The methodology applied in nutritional science, isolating compounds and testing their effects individually, is laughably inadequate. And as to the implementation of these findings, search for "Folic Acid Linked To Increased Cancer Rate" and then tell me how they can just add in vitamins later. The problem isn't recreating biological processes, it's knowing what to recreate, with what compounds, and in what quantity.